Integrated spike/drip chamber structures are well known. In these known systems, the spike is inserted into the intravenous fluid reservoir, and the drip chamber is connected to a tube, through which the intravenous fluid flows to the patient. Typically, a puncture site is provided along this tubing, so that a second source of intravenous fluid (containing, for example, medication) can be provided to the patient. If it is desired to provide the second source of intravenous fluid to the patient in lieu of the first until the second source is exhausted, the arrangement shown in FIG. 1 may be used. A duckbill (one-way) valve 14 is provided in the tubing above the puncture site 15 and below the drip chamber 12 for the first source of intravenous fluid 11, and the second source 17 is hung at a higher level than the first 11. With this arrangement, the higher head pressure of the second source 17 forces the duckbill valve 14 closed so that only the second fluid flows to the patient until the second fluid is exhausted. At this point the duckbill valve 14 opens and allows the first fluid to flow to the patient. Such an arrangement allows one to keep the vein open with intravenous fluid until it is desired to administer the medication, and it allows the continuation of intravenous fluid flow to the vein immediately after the medication is depleted. In order to control the flow rate of the intravenous fluid, a clamp 16 may be placed below the puncture site 15. Typically, such clamps are simply placed on the tubing 19 and control the flow by squeezing the tubing 19. Placing the clamp 15 between the puncture site 15 and the drip chamber 12 may cause problems in the administration of intravenous fluid. In these systems, the various components (e.g., the duckbill valve 14, the filter 13 and the puncture site 15) are each separately disposed in the intravenous tubing 19, such that both ends of each component must be cemented to the tubing 19.